Concrete is exceptionally strong under compression, but reinforcement is often required to provide the tensile performance needed for structural applications. For generations, steel rebar has been the standard reinforcement material used in concrete construction.

Today, fiberglass reinforced polymer (FRP) provides another option.

FRP reinforcement offers high strength at a fraction of the weight of steel while eliminating one of steel reinforcement's most persistent problems: corrosion. For infrastructure, flatwork, masonry, and other applications exposed to moisture, chlorides, chemicals, or other aggressive conditions, these characteristics can provide significant advantages over conventional steel.

Why Steel Rebar Corrodes

Steel and concrete work well together structurally, and their similar coefficients of thermal expansion have helped make reinforced concrete one of the world's most common construction materials.

The challenge is what happens when steel reinforcement begins to corrode.

Concrete is porous. Over time, moisture, oxygen, chlorides, and other contaminants can reach embedded reinforcing steel. As corrosion develops, the steel loses material and the resulting rust occupies greater volume than the original steel. This expansion creates internal pressure within the surrounding concrete.

Eventually, that pressure can contribute to cracking, delamination, and spalling. Once deterioration begins, additional moisture and contaminants can reach the reinforcement, accelerating the process.

The result can be a cycle of inspection, repair, and rehabilitation throughout the service life of the structure.

Steel also presents practical challenges during construction. Its weight increases transportation and handling requirements, and installation can require significant labor and equipment. Steel is also electrically and thermally conductive, which can make it less desirable for certain specialized applications.

How Fiberglass Reinforcement Is Different

Fiberglass reinforced polymer (FRP) composites combine high-strength glass fibers with a durable thermoset resin matrix. Pultrusion allows these materials to be manufactured continuously with reinforcement strategically oriented to provide strength where it is needed.

The resulting FRP components provide several characteristics that make them attractive for concrete reinforcement and strengthening applications.

Corrosion Resistance

FRP does not rust. Fiberglass reinforcement can withstand exposure to moisture, chlorides, and many chemicals without experiencing the electrochemical corrosion associated with reinforcing steel. This is particularly valuable for applications exposed to deicing salts, coastal environments, wastewater, chemicals, or persistent moisture.

Lightweight Construction

Fiberglass reinforcement weighs substantially less than steel. Depending on the product and application, FRP can weigh 75-80% less than comparable steel materials. Lower weight can reduce transportation costs and make material easier for construction crews to unload, move, position, and install.

High Strength-to-Weight Ratio

Despite its low weight, properly engineered FRP provides excellent tensile properties and a high strength-to-weight ratio. This allows engineers to take advantage of strong reinforcement without adding the weight associated with traditional steel components.

Non-Conductive and Electromagnetically Transparent

Fiberglass is electrically non-conductive and electromagnetically transparent. These characteristics can be particularly valuable around electrical infrastructure, sensitive equipment, communications systems, and other applications where metallic reinforcement may interfere with system requirements.

Reduced Maintenance

Because fiberglass does not rust, FRP reinforcement can eliminate corrosion-related maintenance associated with reinforcing steel. Over the life of a structure, that can contribute to reduced maintenance requirements and lower lifecycle costs.

Where Can Fiberglass Reinforcement Be Used?

FRP reinforcement is not a single product intended to replace steel in every situation. Different applications require different reinforcement strategies. Strongwell manufactures several engineered composite products for specific concrete reinforcement and strengthening applications.

COMPOSIBAR® Fiberglass Rebar

COMPOSIBAR composite fiberglass rebar is designed specifically for concrete reinforcement in flatwork and masonry applications.

Manufactured in the USA using a patented process, COMPOSIBAR combines high-strength fiberglass with a thermoset resin system to provide a lightweight, corrosion-resistant alternative to conventional steel rebar.

COMPOSIBAR weighs approximately 74% less than comparable steel rebar and is tested to meet the physical and mechanical requirements of ASTM D7957.

Typical applications include:

• Slabs-on-grade
• Parking lots
• Sidewalks and pedestrian pathways
• Curbs and gutters
• Driveways
• Patios and pool decks
• Agricultural slabs
• CMU walls
• Footings and foundations

COMPOSIBAR can be installed using many of the same construction practices used with steel reinforcement, including conventional ties and chairs. Plastic or composite accessories can also be used when maximum corrosion resistance is desired.

For projects where corrosion, material weight, or electrical conductivity are concerns, fiberglass rebar can provide a practical alternative to conventional reinforcing steel.

GRIDFORM™ Bridge Deck Reinforcement

For concrete bridge decks, Strongwell offers GRIDFORM, a prefabricated FRP reinforcement system designed to replace conventional steel reinforcement. GRIDFORM consists of two layers of pultruded FRP grating separated by shear connectors. An integral stay-in-place form can be incorporated into the system, simplifying construction while providing corrosion-resistant reinforcement throughout the bridge deck.

The bidirectional reinforcement panels weigh approximately 4.7 pounds per square foot, making them considerably easier to handle than comparable steel reinforcement assemblies.

Because GRIDFORM does not rust, the system is particularly attractive for bridge decks exposed to moisture and deicing salts, two conditions that can contribute significantly to deterioration of conventional reinforced concrete infrastructure.

SAFSTRIP® Structural Strengthening Strip

Not every project involves new concrete construction. Existing concrete structures may need additional reinforcement because of changing loads, deterioration, design modifications, or rehabilitation requirements.

SAFSTRIP is an externally applied composite strengthening strip designed to increase the flexural and load-bearing capacity of existing concrete girders, slabs, and decks. The product combines carbon tows with fiberglass mats and rovings in a corrosion-resistant composite strip. SAFSTRIP is mechanically fastened to the existing structure, requiring minimal surface preparation compared with many bonded reinforcement systems. The material can also be drilled without splitting or delaminating, simplifying field installation.

Fiberglass or Steel: Which Reinforcement Is Better?

There is no universal reinforcement material for every concrete structure. Material selection should be based on structural requirements, applicable codes and standards, environmental exposure, installation requirements, expected service life, and project economics.

Steel remains a familiar and widely available reinforcement material. However, FRP offers important advantages when corrosion resistance, low weight, electrical non-conductivity, or long-term maintenance are priorities.

The comparison becomes particularly compelling when lifecycle performance is considered. A reinforcement system that does not rust can help address one of the fundamental causes of deterioration in reinforced concrete structures.

For that reason, fiberglass reinforcement is increasingly being considered not simply as a substitute for steel, but as an engineered material selected for applications where its unique properties provide greater long-term value.

Fiberglass Structural Reinforcement from Strongwell

Strongwell has been manufacturing pultruded fiberglass products in the United States since 1956. Today, the company combines pultrusion manufacturing, engineering, fabrication, and extensive in-house testing capabilities to develop FRP solutions for infrastructure and construction applications.

From COMPOSIBAR fiberglass rebar for flatwork and masonry to GRIDFORM bridge deck reinforcement and SAFSTRIP structural strengthening systems, Strongwell offers multiple approaches to improving the durability and service life of concrete structures.

Learn more about Strongwell's structural reinforcement products or contact Strongwell to discuss the requirements of your application.